Since the Symfony framework project has such tight integration with both the Propel and Doctrine ORM layers, they thought they'd share some statistics on the usage of both as mapped through the stats from their Jobeettutorial.

As for any Open-Source community, it's not easy to find metrics that tell you what people use and how they use it. You can measure the number of tickets for a specific feature, count the number of people asking for help on Propel or Doctrine. But for the Propel vs Doctrine question, we have two more reliable metrics.

As is shown in this graph of the total Jobeet traffic in 2009, Doctrine is winning by a long shot. That's not to say that you can't still use Propel is that's what you and your application are using, this is just showing the overall popularity of each of the ORMs.